Resin bottles, representatives of which are Oriented PolyPolypropylene (OPP) bottles and Poly-Ethylene Terephthalate (PET) bottles, are used in various fields, such as beverages, foods, cosmetics, and so forth. Such a bottle is generally formed in a predetermined shape by biaxially stretch blow molding a resin preform by using a blow molding device. The resin preform has been formed in a bottomed tubular shape by, for example, injection molding.
The blow molding device includes: a blow molding mold to which a preform, after heated to a temperature at which the preform is stretchable, is fitted; a blow nozzle that is fitted to a mouth tubular portion of the preform fitted to the mold; and a pressurized liquid supply unit configured to supply a pressurized liquid to the blow nozzle. By filling the pressurized liquid into the preform through the blow nozzle, the preform is stretched axially and radially into a shape conforming to a cavity of the mold.
One example of such a blow molding device is the one, as described in Patent Literature 1, that uses a pressurized liquid, instead of pressurized air, as the fluid that is filled into the preform. In this case, by using a content liquid, such as a beverage, a cosmetic product, a pharmaceutical product, or the like, that is to be filled in a final product as the liquid, the step of filling the content medium to the bottle may be omitted, and the production process and the configuration of the blow molding device may be simplified.